A recording magnetic head of a vertical magnetic field recording type that magnetizes a recording medium in the vertical direction has a first magnetic layer whose front surface is formed in a first direction with a predetermined width on a facing surface, the facing surface being disposed so as to oppose the recording medium.
FIG. 14 is a schematic perspective view showing a conventional recording magnetic head of vertical magnetic recording type. In the recording magnetic head of vertical magnetic recording type, on the facing surface F toward a recording medium, a first magnetic layer 1 (a main magnetic pole layer) and a second magnetic layer 2 face each other with a gap therebetween in the direction of a film thickness. A front surface of the first magnetic layer 1 is formed on the facing surface with a predetermined width in the first direction. Further, although not shown in FIG. 14, a coil layer is formed between the first magnetic layer 1 (the main magnetic pole layer) and the second magnetic layer 2. An induced magnetic field generated when electric current flows through the coil layer is induced in the first magnetic layer 1 (the main magnetic pole layer) and the second magnetic layer 2, and a recording magnetic field is incident on the recording medium in a direction vertical to the recording medium surface from the front surface of the first magnetic layer 1. The recording magnetic field reaches the second magnetic layer 2 after passing through the recording medium.
In the first magnetic layer 1 (the main magnetic pole layer) of the magnetic head shown in FIG. 14, the angle formed between a side surface 1d of a front portion S1 and the facing surface toward the recording medium is larger than the angle formed between a side surface 1e of an inclined portion S2 and the facing surface toward the recording medium. The angles are measured with respect to the facing surface with a sense of rotation such that a maximum angle is 90°. A rear portion S3 which is wider than the front portion S1 is formed at the rear side of the inclined portion S2.
As shown in FIG. 14, below the first magnetic layer (the main magnetic pole layer) 1, a slider which mounts the magnetic head is arranged, and the recording medium moves from the bottom to the top (in the figure). In FIG. 14, the downward direction is a leading side L and the upward direction is a trailing side T.
When a direction orthogonal to the first direction is a second direction (Y direction in the figure), in the first magnetic layer 1, a length L1 of a trailing upper surface 1b of the front portion S1 in the second direction is equal to a length L2 of a leading lower surface 1c of the front portion S1 in the second direction.
FIG. 15 is a schematic perspective view showing another conventional magnetic head. The magnetic head is also a recording head of vertical magnetic recording type, and similar to the magnetic head in FIG. 14, a first magnetic layer 3 and a second magnetic layer 2 face each other. A coil layer provided between the first magnetic layer 3 and the second magnetic layer 2 is omitted from the figure.
In the first magnetic layer 3, the length L1 of a trailing upper surface 3b of the front portion S1 in the second direction (Y direction in the figure) is shorter than the length L2 of a leading lower surface 3c of the front portion S1 in the second direction.
Japanese Unexamined Patent Application No. 11-250416 (Page 3, FIG. 1) is an example of related art. In the vertical magnetic recording field type, in forming a recording magnetized pattern on the recording medium, a recording magnetic field generated from a trailing edge of a front surface 1a of a first magnetic layer (a main magnetic pole layer) is dominant.
FIG. 16A is an enlarged fragmentary side view of the vicinity of the first magnetic layer (the main magnetic pole layer) 1 and the second magnetic layer 2 in the magnetic head shown in FIG. 14, FIG. 16B shows a magnetic field distribution of a recording magnetic field generated from the front surface of the main magnetic pole layer at the facing surface F toward the recording medium, and FIG. 16C is a plan view of a recording track on the recording media on which signals are recorded by the magnetic head.
As shown in FIG. 16, if the length L1 of a trailing upper surface of the front portion S1 in the second direction is equal to the length L2 of a leading lower surface of the front portion S1 in the second direction, a generated magnetic field of the trailing upper surface is strengthened, and then the width of a recording track on the recording medium caused by side fringing and magnetic field permeation of the recording magnetic field at the trailing side becomes larger than a width Tw of the front surface of the first magnetic layer 1 (the main magnetic pole layer), which causes a problem that a practical track width Tv increases.
FIG. 17A is an enlarged fragmentary side view of the vicinity of the first magnetic layer 3 and the second magnetic layer 2 in the magnetic head of FIG. 15. FIG. 17B shows a magnetic field distribution of the recording magnetic field generated from the front surface of the first magnetic layer 3 at the facing surface F toward the recording medium, and FIG. 17C is a plan view of the recording track on the recording medium.
As shown in FIG. 17, if the length L1 of the trailing upper surface 3b of the front portion S1 in the second direction is shorter than the length L2 of the leading lower surface 3c of the front portion S1 in the second direction, the generated magnetic field of the trailing upper surface 3b becomes much stronger than that of FIG. 16, which causes a problem that the practical track width caused by side fringing and magnetic field permeation of the recording magnetic field at the trailing side becomes larger.
FIG. 18 shows an enlarged fragmentary side view of the vicinity of an upper magnetic pole layer 4 (a main magnetic pole layer) and a lower magnetic pole layer 5 in the magnetic head disclosed in Japanese Unexamined Patent Application No. 11-250416, and a magnetic field distribution of the recording magnetic field generated from a front surface of the upper magnetic pole layer 4. As shown in FIG. 18, Japanese Unexamined Patent Application No. 11-250416 discloses a recording head in which the front surface 4a of the upper magnetic pole layer 4 becomes an inclined surface or a stepped surface which is away from the recording medium from the leading side L toward the trailing side T. According to Japanese Unexamined Patent Application No. 11-250416, the trailing side of the upper magnetic pole layer 4 can be kept away from the recording medium to decrease the generated magnetic field at the trailing side of the upper magnetic pole 4. However, as shown in FIG. 18, the magnetic field distribution of the recording magnetic field generated from the front surface of the upper magnetic pole layer 4 is concentrated on the vicinity of a gap 6 which makes it difficult to supply a sufficient amount of recording magnetic field to the recording magnetic medium.